Aerobic exercise attenuates blood pressure reactivity to cold pressor test in normotensive, young adult African-American women.

Exaggerated blood pressure reactivity to behavioral stress has been observed in the African-American population, and such a pressor response is believed to play a role in hypertension. Regular aerobic exercise has been shown to exert an anti-hypertensive effect, and this may alter the blood pressure hyperreactivity observed in African Americans. To test the hypothesis that aerobic exercise attenuates pressor reactivity in African Americans, we studied eight healthy aerobically-trained normotensive African-American females and five similar sedentary females. The stress stimuli consisted of the cold pressor test with the foot immersed in ice water for two minutes. The aerobic exercise training protocol consisted of six weeks of jogging at 60-70% of peak oxygen uptake (VO2peak), three days/week for 35 min/exercise session. Systolic blood pressure, diastolic blood pressure, mean arterial blood pressure, heart rate, cardiac output, total peripheral resistance, and forearm blood flow were measured. Manifestation of a training effect was illustrated by a 24.1 +/- 0.2% increase in VO2peak (26.9 +/- 1.2 mL x kg(-1) min(-1) vs 35.4 +/- 1.6 mL x kg(-1) min(-1)) (P<.05). Within the exercise-trained group there was a 6.3 +/- .15% decrease in systolic pressure (129 +/- 4.6 mm Hg vs. 121 +/- 5.4 mm Hg) (P<.05), and a 5.0 +/- .05% decrement in mean arterial blood pressure (99 +/- 3.3 mm Hg vs 94 +/- 3.6 mm Hg) (P<.05) during the cold pressor test. Pressor reactivity to cold stress did not change in the untrained group. Measures of heart rate, cardiac output, total peripheral resistance, and forearm blood flow were unaltered during conditions of the cold pressor test. We conclude that aerobic exercise attenuates the blood pressure reactivity to behavioral stress in young, adult normotensive African-American females. A lifestyle change such as exercising may play a role in reducing the risk of hypertension in African-American women.

Aerobic capacity during two-arm and one-leg ergometric exercise.

Previous studies have shown that maximal oxygen uptake (VO2 max) measured during two-arm cranking and one-leg cycling is about 70-78 per cent of VO2 max measured during two-leg cycling. The present study investigated the maximal physiological responses of eight healthy untrained males during two-arm, one-leg, and two-leg ergometric exercise. Two-arm cranking and one-leg cycling were found to be 55 and 66 per cent of two-leg VO2 max, respectively. The % VO2 max at which the anaerobic threshold occurred during the two-arm and one-leg exercise conditions were 57 and 68 per cent, respectively. These findings suggest that when the active muscle mass is limited, a progressive exercise test using one leg may elicit a higher VO2 max than with two arms.

Maximal oxygen intake estimated from submaximal heart rate.

This study investigated the predictability of maximal oxygen intake from three different submaximal heart rates assessed during an initial and follow-up ride on a cycle ergometer. Twenty-four healthy male subjects performed workloads of 600, 750, and 900 kpm's for six minutes on each of two visits to the laboratory. Analysis of variance for a randomised complete blocks design, with subjects constituting blocks, was used to analyse heart rate, estimated maximal oxygen intake, and residual estimated maximal oxygen intake variations among the experimental conditions. Relationships between the actual and estimated maximal oxygen intakes were determined using the Pearson Product-Moment formula of correlation. The average estimated maximal oxygen intake was significantly increased from the first testing occasion to the second. Although errors of estimation decreased significantly (450 ml to 366 ml) in favour of the second testing condition, the decrease was neither consistent with workloads nor subjects. The correlation coefficients were consistently low at 600 kpm for both testing occasions (0.68 and 0.73, respectively), consistently high at 750 kpm (0.82 and 0.84, respectively), and quite variable at 900 kpm (0.71 and 0.84, respectively), indicated that the validity of the nomogram was not consistent with all workloads or testing occasions. Despite these inconsistencies, the nomogram is, for practical purposes, a valid predictor of maximal oxygen consumption.